Air filter



FIG. 1 is a perspective view of an air filter showing my new design;

FIG. 2 is a front elevational view thereof, the rear being a mirror image;

FIG. 3 is a left side elevational view thereof, the right side being a mirror image;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a front, bottom perspective view thereof, the rear bottom being a mirror image.

The air filter is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design. 

CLAIM The ornamental design for an air filter, as shown and described. 